Premium
Minimal alveolar concentration of sevoflurane for maintaining bispectral index below 50 in morbidly obese patients
Author(s) -
ZEIDAN A.,
MAZOIT J. X.
Publication year - 2013
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/aas.12038
Subject(s) - medicine , bispectral index , sevoflurane , propofol , anesthesia , body mass index , confidence interval , fentanyl , tracheal intubation , minimum alveolar concentration , morbidly obese , pharmacokinetics , obesity , intubation , pharmacodynamics , sufentanil , weight loss
Background Morbid obesity is associated with important differences in pharmacokinetics and pharmacodynamics. The aim of this study was to determine minimum alveolar concentration of sevoflurane for maintaining bispectral index ( BIS ) below 50 ( MAC BIS50 ) in morbidly obese patients undergoing bariatric surgery using the C ontinual R eassessment M ethod ( CRM ) method. Methods Twenty‐four morbidly obese patients (body mass index 40–70 kg/m 2 ) were enrolled in our study. Twenty minutes following pre‐medication with fentanyl 100 μg, general anaesthesia was induced using propofol 2 mg/kg and cisatracurium 2 mg/kg to facilitate tracheal intubation. The lowest BIS score was recorded following induction. Thereafter, when BIS began to increase > 60, maintenance of anaesthesia was started with a pre‐determined end‐tidal sevoflurane concentration ( E T Sevo ) and maintained for 10 min followed by 1‐min assessment of BIS taken at 10‐s intervals to determine the E T Sevo . The E T Sevo leading to a probability close to 80% success was calculated using the CRM , and the MAC BIS50 leading to 50% success was calculated by fitting the data to a dose‐probability sigmoid curve, respectively. Results The E T Sevo able to maintain BIS value below 50 was 1.8% in 67% [95% confidence interval ( CI ) 0.44–0.86] and higher in the remaining 33% of the patients and the E T Sevo leading to a BIS value below 50 in 50% of the patients ( MAC BIS50 ) was 1.6 ± 0.10%. Conclusions The calculated values (1.8% and 1.6%) were higher than that previously reported in normal adult patients (0.97%; 95% CI 0.89–1.1%) and less than that reported in children (2.8%; 95% CI 2.7–3.1%).